Passive Infrared Detection of Microburst Induced Low Level Wind Shear.

摘要

During the past two decades the aviation community has come to recognize the microburst, as an extreme hazard to aviation. When an aircraft encounters a microburst during the critical landing or takeoff stages, a strong head-wind to tail-wind shear is experienced along with a coupled severe downdraft. If the shear is severe enough, the aircraft may crash due to loss of lift. The purpose of this thesis is to determine theoretically, the microburst detection capabilities of a passive infrared (IR) radiometer system. The proposed system detects a cold microburst based on its temperature difference as compared to the ambient environmental temperature. Also, a ranging technique (employing weighting functions) is examined. Also included in this study is a general overview of atmospheric transmission characteristics as applied to the infrared 12.5 -15micron portion of the electromagnetic spectrum. This part of the spectrum seems well suited for this microburst application and contains only two significant atmospheric absorbers; CO2 and atmospheric water vapor. Various microburst atmospheres are modeled using a customized application of the radiative transfer equation. These modeled atmospheres are divided into two categories: (1) High Plains or relatively dry boundary layers and (2) south-east United States systems that are characteristically more water saturated than the high plains environment. Radiance and transmission calculations are accomplished using the Air Force Geophysics Laboratory code FASCOD2. (jhd)